Steroid-sensitive nephrotic syndrome (SSNS) has been postulated to have an immunopathogenic basis. To determine whether SSNS is associated with specific class II antigens of the major histocompatibility complex, we studied HLA-DR and DQ in 40 children with SSNS. HLA-DR7 was found in 40% of SSNS patients compared with only 11.23% of controls (P = 0.00025). HLA-DR9 occurred in 71.40% of patients with frequent relapses, compared with 27.37% of controls (P = 0.016). It seems likely that SSNS has an immunogenetic basis.